Distinguished RZ-OOK Performances Between DFBLD Pulsed Carriers Self-Started by Gain Switching and Nonlinear Absorption Modulation

The distinguished transmission performances of the return-to-zero (RZ) on-off-keying data stream at 10 Gb/s carried on the nonlinearly modulated and gain-switched distributed feedback laser diode (DFBLD) pulse train triggered with a self-feedback optoelectronic oscillator (OEO) are compared. The OEO driven gain-switching DFBLD with insufficient pulse extinction is not particularly suitable for RZ data generation owing to its intense relative intensity noise (RIN) and large timing jitter under threshold operation. In contrast, the nonlinearly driven electroabsorption modulator delivers a self-pulsated RZ carrier with smaller timing jitter of 600 fs, shorter pulsewidth of 21 ps, higher pulse on/off extinction ratio up to 9.8 dB, and a better receiving power sensitivity of -20 dBm for bit error rate <;10^-9 as compared to the gain-switched DFBLD based RZ carrier. In comparison with the gain-switching technique, the nonlinear absorption modulation greatly reduces the peak-to-peak frequency variation and chirp parameter of the self-pulsated RZ carrier to -12 GHz and -0.32, respectively.